#qi-hardware IRC log for Sunday, 2010-10-24

wpwrak: my report about case insensitive matching in the field contents or part number matching was wrong. no need to investigate. sorry I was confused about a few things, but it's all clear now and all those comparisons are case sensitive.

wpwrak: my previous attepmts at rev-engineering the usb protocol were troubles with linux < 2.6.21, that did not have a system (without patching) that captured *whole* frames. in the 2.6.35 I use I could do that. And luckily wireshark handles very well USB, and I did not have to solve the usb frames directly from usbmon.

well, it's a distributed version control system, where some actions you do with command line (as svn, git, ...), and for some others it has a small web server, and then you do the tasks with a web browser. It has not only distributed version control of code, but also wiki, ticket system, ... Then I wrote a php script that fetches feeds and writes them in 'wiki files', than then the usual fossil webserver will serve nice for lynx to browse.

wolfspraul: as you see, I have that in a web server. So I can read the same from a computer with internet access (browsing to my server page), with my PC (that has a copy of the repository synchronizable), or with the nanonote, that can be synchronized with the PC. Three places of reading.

hmm .. now an electrical engineering puzzle: i have a 50 Ohm transmission line, about 1-2 m long. my termination is something like 1 MOhm, and i can't just toss in a resistive divider because i need to (more or less) preserve the amplitude. the signal is aperiodic. if there *anything* i can do ? :)

with all the things I learnt with the cable, I feel ready to jump into a bigger project like xue and help there, boomify stuff, clean kicad fields, extend fully characterized matching to more types, etc.

the way to do it would be to define an equvalence for the vendor part to the digi-key part, with the same part number as in the schematics. that way, you don't need to go via the "private" equivalence and you don't need to tweak the value

not that i'd mind to have something with nicer selection to compete with eeschema. pcbnew will be harder to beat, though. there's a fair amount of magic that went into all those "magnetic" and "trace-hugging" functions

well, in many cases, that's fine. e.g., schematics and simualation of the same circuit may look very different. add a cap here for parasitic capacitance, replace an MCU with a resistor for input port leakage, etc.

but the basic gui interactions of kicad have a number of design concepts that just don't work well. like the weird way to do block ops, the clumsy concept of proximity in pcbnew, or the ordering of choices in ambiguous selections.

kristianpaul: then, if there's an ambiguity, it pops up a selection. that's an improvement, because it make a more or less arbitrary pick before. but ... the selection is often redundant. e.g., if i'm about to delete a trace, it doesn't really matter on which segment i click. so if i hit an area where >= 2 segments could be selected, it could notice that they both have the same effect and not ask. this happens very very often.

kristianpaul: then, if object A overlaps object B at the point we click on, but A is by nature larger than B (e.g., A is a component while B is a trace), then it could give just priority to B, without looking at A.

kristianpaul: then, all block operations are by rectangle. there's no way to add/remove items from a selection or to combine selections. one consequence of this is that you now need a menu that lets you select what type of things you really wanted to include, because you often have some "bycatch".

just before starting with openmoko, i sent some patches for "hugging" traces. they were good enough to look exciting but broken enough to still need a month or two of work. luckily, someone picked them up and fixed them for me ;-)

since then, kicad development has taken a turn i don't like so much. the code is better structured by the coding style has become incredibly ugly, in my opinion. basically the diametral opposite of the linux kernel coding style.

kristianpaul: i measured the fastest bitbanging speed for a single gpio and i got about 1 MHz. from that, i concluded that i'll never have the slightest risk of going too fast :) (the interface can do 8 MHz, if memory serves me)

hmm does anyone know if there's a way to make a pattern rule in gnu make that's equivalent to %.foo: %/%.bar ? (this doesn't work, because gnu make only substitutes the first % in %/%.bar. since this substitution is done after all other expansions, i can't trick it with $(subst ...) or such either)

third, the mini-usb connector symbol is quite ugly. to make it even more weird, it has two unused pins that don't correspond to anything in the footprint either. how about stealing the one from gta02-core or ben-wpan (the latter got it from the former) ?

fifth, (that's something inherited from kicad) you have a nice example for the trouble with the default symbols when you look at the font sizes in FB2, then C27, and finally +3.3V (all are near each other)

kristianpaul: I found that for some videos mplayer shows the first frame for several seconds (maybe 10) until it continues okey.. so if you see this behaviour that is okey. I mean, it is the same thing I get.. no idea why. Maybe it is mplayer, maybe it is that video, maybe it is theora.. who knows